Pyhäjärvi is a municipality in the south of Oulu province, Finland. Pyhäjärvi also borders the Eastern Finland and Western Finland provinces. The town belongs to the subregion of Nivala-Haapajärvi.
As the highway 4 (E75), the highway 27 and the Ylivieska-Iisalmi railway all run through the town, Pyhäjärvi is well situated in an intersection of communication and transport services. The town has also an airfield equipped for instrument flying.
The town of Pyhäjärvi, was founded in 1866, and it was then named after lake Pyhäjärvi, a lake of 125 km² and rich in fish. Pyhäjärvi became officially a town January 1993. The town has about 6,321 inhabitants (2003), of whom some 60 percent live in the two population centre Pyhäsalmi and Ruotanen.
See also: Lake Pyhäjärvi